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Physico chemical processing of
(hazardous) waste
WASTE
MANAGEMENT
AND
TECHNOLOGY
Martin Kubal
Mecislav Kuras
Institute of Chemical
Technology in Prague
Waste is classified as hazardous if:
- it is listed in the Hazardous Waste List;
- it is mixed with or contaminated by any of the components listed in the
Hazardous Waste List;
- it should display one or more of the hazardous properties.
Cause of hazard – occurence of dangerous chemicals and their mixtures.
Most dangerous – hazardous waste from industry, especially from chemical
industry and other industries dealing with chemical processes (metallurgy,
pharmacy, petrochemistry, glass, machinery, etc.) containing mixtures of
chemicals often of unknown composition and origin.
Treatment of them requires special approaches with higher cost and health and
environmental risk.
Effects: Hazardous waste is a waste which may pose a substantial present or
potential hazard to human health or the environment when impropoperly treated,
stored or disposed of, or otherwise mismanaged.
hazardous waste origin and effect
hazardous waste – EU definition
Council Directive 91/689/EEC of 12 December 1991 on hazardous waste:
For the purpose of this Directive 'hazardous waste` means:
- wastes featuring on a list to be drawn up in accordance with the procedure laid down
in Article 18 of Directive 75/442/EEC on the basis of Annexes I and II to this Directive,
not later than six months before the date of implementation of this Directive. These
wastes must have one or more of the properties listed in Annex III. The list shall take
into account the origin and composition of the waste and, where necessary, limit values
of concentration. This list shall be periodically reviewed and if necessary by the same
procedure,
- any other waste which is considered by a Member State to display any of the
properties listed in Annex III. Such cases shall be notified to the Commission and
reviewed in accordance with the procedure laid down in Article 18 of Directive
75/442/EEC with a view to adaptation of the list.
Properties of wastes which render them hazardous*explosive, oxidizing, highly flamable, flamable, irritant, harmful, toxic, carcinogenic,
corrosive, infectious, teratogenic, mutagenic, substances and preparations which
release toxic or very toxic gases in contact with water, air or an acid, substances and
preparations capable by any means, after disposal, of yielding another substance, e.g. a
leachate, which possesses any of the characteristics listed above, ecotoxic
*see appendix at the end of presentation
The total amount of waste produced in the European Union is currently about
1 800 000 000 tonnes per year. Approximately 90 000 000 tonnes of this waste is
hazardous.
Czech Republic in 2010*:
hazardous waste - production
total (tons) category of waste
hazardous
(tons)
other (tons)
production of waste 24 123 560 1 370 679 22 752 881
manufacturing industry
(including chemical industry)
4 202 463 550 376 3 652 088
waste and water management 2 507 187 550 690 1 956 497
municipal waste 3 334 240 5 028 3 329 212
* Statistical Yearbook of the Czech Republic
hazardous wastes - significant part of industrial wastes,
especially wastes of chemical character
The approach used to develop systems to treat and dispose of industrial
wastes is distinctly different from the approach used for municipal wastes.
There is a lot of similarity in the characteristics of wastes from one
municipality, or one region, to another. Best approach to designing a
treatment system for municipal wastes is to analyze the performance
characteristcs of many existing municipal systems and deduce an optimal
set of design parameters for the system under consideration.
In the case of industrial wastes, however, few industrial plants have a high
degree of similarity between products produced and waste generated.
Therefore, emphasis is placed on analysis of the wastes under
consideration, rather than on what is taking place at other industrial
locations.
character of industrial wastes
Wastes from industries are customarily produced as:
- liquid wastes (process wastes, which go to an on-site or off-site
wastewaster treatment systems),
- solid wastes (including hazardous wastes, which include some liquids)
- air pollutants
These wastes are managed and regulated differently depending on the
characteristics of the wastes and process producing them. The three phases
of wastes are closely interrelated, both as they are generated and managed
by individual industrial facilities. Industrial wastes that are discharged to
neither air nor water are classified as solid, industrial or hazardous wastes.
Interrelation of industrial wastes categories - examples
Solid wastes disposed of in the ground can influence the quality of
groundwater and surface waters by way of leachate entering groundwater
and traveling with it through the ground, then entering a surface water body
with groundwater recharge.
Volatile organics in that recharge water can contaminate the air. Air
pollutants can fall out to become surface water or groundwater pollutants,
and water pollutants can infiltrate the ground or volatilize into the air.
Additionally, waste treatment proces can transfer substances from one of the
three waste categories to one or both of the others.
Waste treatment or disposal systems themselves can directly impact the
quality of the air, water or ground.
Methods for treating industrial liquid wastes -
three categories
Chemical methods - changing the chemical structure involve
exchanging or sharing electrons between atoms.
Physical methods - without necessarily changing the chemical
structure of substances.
Biological methods - involve living organisms like bacteria or other
microorganisms using organic or, in some instances, inorganic
substances for food. In so doing , the chemical and physical
characteristcs of the organic and/or inorganic substances are changed.
In being so used, complex organic molecules are systematically
broken down, than reassembled as new cell protoplasm.
Treatment of air discharges from industry
The discharge, or release, of substances to the air, no matter how slight, is
regarded as air pollution. Discharge can be direct, by means of a stack,
vent, hood, or the like, or indirect, by way of leaks from a building´s
windows, doors, or other openings(fugitive emissions). Fugitive emission
must be considered to evaluate a facility total emissions.
Methods used for controlling particulate emissions:
- gravity and inertial separators, including so-called cyclones are dry, „no-
moving parts“ devices. They take advantage of the relatively high specific
gravity of certain types of particulate matter, incl. fly ash, dust, cement
particles, and organic solids,
- electrostatic precipitators which take advantage of the electrostatic
charge on the surface of particles
- fabric filters, which make use of physical blocking and adsorption,
- wet scubers, which make use of a liqiud to entrap particulate, thus
removing them from a gas stream.
Solid waste treatment and disposal
If a manufacturing process generates „scrap“ that cannot be reused, it may
be treated as solid waste. When a final residue is produced that cannot be
further treated or disposed of economically on-site, it must be shipped off-
site for disposal.
Disposal of final treatment residues and plant wastes in general depends on
the source and chemical characteristic of the waste material itself. Thus, the
first step is to determine into which category the waste belongs:
- hazardous waste, having one of the hazarous properties determined by
law,
- nonhazardous solid waste.
There are a lot of industrial wastes that must be classified as hazardous
wastes. Hazardous wastes are typically the most toxic, expensive and
regulated type of industrial waste.
Industrial nonhazardous waste do not meet the definition of hazardous
waste, but they are excluded from most municipal landfills because of their
physical and chemical characteristics.
„Physico-chemical treatment“ is defined in the EU legislation (Directive
2008/98/EC, which repealed Directive 2006/12/EC) as a waste disposal
operation:
„D 9 Physico-chemical treatment not specified elsewhere in this Annex which
results in final compounds or mixtures which are discarded by means of any of the
operations numbered D 1 to D 12 (e.g. evaporation, drying, calcination, etc.)“
Physical and chemical treatments are strongly interrelated. For example a
precipitate of a hazardous waste compound formed by a chemical reaction
is separated from the reaction mixture by physical means such as
sedimentation and filtration.
In order to characterize wastes for physical treatment, it is necessary to
know their chemical properties – pH of wastewater or the chemical
properties of solids that may be dangerously reactive when produced by
the drying of sludges.
Physico-chemical treatments of hazardous waste
Physico-chemical treatment is applied mostly for industrial waste of
chemical character.
One of the first steps to consider in waste treatment is separation, which
can save tremendous amount of effort and expense by resagregating
wastes in forms that can be treated most economically or which may be not
even hazardous. Separation may be as simple as draining an aqueous layer
from organic one in two-phase waste.
Methods of physical treatment
Physical treatment of wastes depends upon the physical properties of the
material treated, as state of matter, solubility in water and organic solvents,
density, volatility, boiling point and melting point. It consists especially of:
phase separation, sedimentation, filtration, membrane separation
(reverse osmosis, nanofiltration, ultrafiltration), sorption by activated
carbon or resin, distillation and stripping, drying and evaporation,
extraction
Physico-chemical waste treatment
Physical, chemical and biochemical treatment option from these three areas are
strongly interrelated. For example, a precipitate of a hazardous waste
compound formed by chemical reaction is separated from the reaction mixture
by physical means, such as sedimentation or filtration.
Before considering physical treatment and their treatment options it is useful to
have an overview of the various kinds of treatment to which hazardous
substances may be subjected, including their advantages and disadvantages.
Safety dictates that the first thing to do with hazardous waste is to consider any
acute hazards that it may pose and take appropriate preventive actions.
Important examples are cyanides and sulfides, which can react with acids or
hydrolyze to give toxic HCN or H2S respectively. Reactive wastes must be
treated with the appropriate reagents to reduce their hazards. One of the first
step to consider in waste treatment is separation.
Separation frequently results in resource recovery that yields materials of
economic value. For example separation of hazardous substances sorbed to
spent activated carbon can give an carbon product that can be reactivated and
used again.
Treatment options
Separation of components of a mixture that are already in two different
phases.
Sedimentation and decantation are easily accomplished with simple
equipment. In many cases the separation must be aided by mechanical
means, particularly filtration or centrifugation. Flotation is used to bring
suspended organic matter or finely divided particles to the surface of a
suspension. Many wastes are composed of aqueous / organic mixtures in
colloidal sized emulsion. An important and often difficult waste treatment
step consists of separation of these components, a process called emulsion
breaking. Acids (including waste acids), other chemical reagents and heat
may all be employed for this purpose.
Once an emulsion is broken, centrifugation can be used to separate the
phases.
Methods of physical treatment
Mixture of undesirable substances or „pollutants“ in water.
Lot of wastes (especially industrial) are in a form of solution or emulsion.
Solution – one or more substances (solutes) dissolved in another medium
(solvent).
When dissolved, the solutes become distributed uniformly throughout the
solvent volume.
Substances that ionize into cations and anions (e.g. sodium chloride) are
soluble in polar solvents such as water (hydrophilic substances).
Substances that do not ionize (oils) are poorly soluble in polar solvents but
highly in non-polar solvents (hydrophobic substances).
Emulsions – hydrophobic substances can be induced to go into a state that is
equivalent in many way to a water solution by emulsification. Emulsion is
equivalent to solution in that it consists of a stable mixture that will not separate
under quiescent conditions. As a mixture flows from one place to another , it
does not change in character. Two ways to accomplish emulsification:
- with emulsifying agent (detergent)
- to mix hydrophobic substance with water together vigorously
Emulsion decomposition (water and oil phases) – heating or aditives.
Waste forming aqueous / organic mixtures
Stable mixture – pollutants will not settle out of water under gravity
(sedimentation).
To treat water – another processes than simple sedimentation.
Effective treatment process – need to recognise forces responsible for the
mixture stability.
Five general types of mixtures:
1. true solution – stability arises from hydrogen bonding between water
molecules and electrical charge of each ion
2. emulsion – caused by emulsifiyng agent (detergent) – link of small
droplets of liquid substance to water – one agent portion dissolved in
water another dissolved in droplets of pollutant
3. emulsion in which stability of droplet pollutant mixture in water arises from
repulsion caused by like electric charges in the droplet surface
4. colloidal suspension – small particles of nonsoluble solid are held away
from each others by repulsive forces of like electric charge on surface of
each solid particle
5. Solution in which ions that would normally not be soluble in water under
prevailing conditions are held in solution by so called chelating agents.
An important type of phase transfer is extraction, including liquid-
liquid and liquid-solid extraction. Transfer of substance from a
solution to a solid phase is called sorption. An important example is
sorption on activated carbon.
Physical precipitation – process in which a solid forms from a solute
in solution as result of physical changes in the solution (cooling the
solution, evaporation of solvents, alteration of solvent composition).
(Compare to chemical precipitation in which a chemical reaction in
solution produces an insoluble material).
Phase transfer or phase transition
Activated-carbon adsorption can be used to remove of wide variety of contaminants
from liquid and gaseous streams (most frequently used for organic compounds). The
process is relative nonspecific, and thus, is widely used as a broad spectrum
treatment operation when the chemical composition of a stream is not fully
understood.
Common treatment application include groundwater treatment, chemical-spill
response, industrial wastewater treatment, air-pollution control system.
Physical adsorption results from the action of van der Waals forces, relatively week
interactions produced by the motion of electrons in their orbitals.
Chemical adsorption or chemisorption , involves electronic interactions between
specific surface sites and solute molecules, resulting in the formation of a bond that
can have all of the characteristics of a „true chemical bond.“
Electrostatic adsorption based on the forces between ions and charged functional
groups and is synonymous with the term ion-exchange.
The adsorption process is reversible - possibility to remove the adsorbed
contaminants after the adsorption capacity of the carbon has been exhausted.
Both result from from electrostatic interaction.
Activated-carbon adsorption
Solvent extraction is referred to two different types of processes:
Liquid-liquid extraction is the separation of constituents from a liquid solution by
contact with another, immiscible liquid in which the constituents are more
soluble.
Liquid- solid extraction (leaching) is the separation of the constituents from
solids by contact with a liquid in which the constituents dissolve.
In hazardous wastes treatment the term „solvent extraction“ is usually
reserved to liquid-liquid extraction, especially extraction of organic compounds
from aqueous solution into immiscible solvents.
Solvent extraction is physical separation process, used for transfer of
constituents from one liquid solution (or solid matrix) to another. The
constituents are unchanged chemically.
Application - for separation of a valuable constituent from impurities present in
the original solution or concentration of a constituent for ease of subsequent
recovery or treatment.
Solvent extraction
Molecular separation is often based upon membrane processes in
which dissolved contaminants or solvent are forced through a
membrane. The most widely used membrane process is reverse
osmosis in which water from wastewater is forced through a
membrane that is selective to water yielding purified water product
and leaving behind a concentrated liquor containing impurities.
Other membrane processes include ultrafiltration and electrodialysis
in which ions in a solution subjected to electrolysis migrate selectively
through alternate membranes that allow for the passage of cations
and anions.
Molecular separation
Membrane separation processes play an increasing role in the reduction or
recycling of hazardous wastes. This processes separate the contaminant (solute)
from a liquid phase (solvent, typically water). Main functions: volume reduction,
recovery or purification of the liqiud phase, concentration or recovery of the
contaminant or solute.
Pressure driven processes:
Reverse osmosis - water separation from a feed stream containing inorganic ions .
The purity of recovered water is relatively high - water is suitable for recycling.
Nanofiltration separates ions or organic components from water by limiting the size
of membrane pores through which a contaminant can pass. Typically used for
removing contaminants with molecular weight 100-500 from water.
Ultrafiltration - separates organic compounds from water according to the size
(molecular weight) of the organic molecules. Membranes are manufactured with the
capability to remove contaminants with the molecular weigh between
100 - 1, 000,000.
Microfiltration - separates with a micrometre sized membrane (0.1 to 10 m)
Electric potential driven processes
Electrodialysis - removes ionic components from water. It produces moderate quality
product water (i.e. several hundred mg/L salts ).
Membrane separation
INLET
PERMEATE
CONCENTRATE
Fundementals of membrane separation
STORAGE
TANK
FILTER
1. STAGE
RO
SOLIDIFICATION/
EVAPORATION
1. PERMEATE
2. STAGE
RO
STORAGE
TANK
FILTER
HCl
2. P
ER
ME
AT
E
1. CONCENTRATE
2. CONCENTRATE
Reverse osmosis
treatment of landfill
leachate
http://www.eco-web.com/edi/090714.html
Pressure driven membrane separation processes
When semipermeable membrane separates two solutions of different
dissolved - solid concentration, pure water flows through the membrane into
the concentrated solution (resulting in osmotic pressure), while ions (i.g.
dissolved salts) are retained behind the membrane. This process is known
as osmosis.
During reverse osmosis, pressure is applied to the more concentration
solution to reverse the normal osmotic flow, and pure water is forced
through the semipermeable membrane into tle less concentrated solution.
The purified stream that passes through the membrane is called permeate,
the concentrated stream retained by the membrane is known as
concentrate.
Advantages of reverse osmosis:
- both the recovered solvent and the concentrates solute can be
recycled to a manufacturing process,
- the separation process does not require an energy-intensive
phase change such as is required for destillation or evaporation
- capital costs are also relatively low.
Membrane separation – reverse osmosis
Ultrafiltration (UF) and nanofiltration (NF) utilise pressure and a semipermeable
membrane to separate nonionic material from a solvent (such as water). These
membrane - separation techniques are particularly effective for the removal of
suspended solids, oil and grease, large organic molecules, and complexed
heavy metals from wastewater stream.
In UF and NF systems, the membrane retains material based solely on size,
shape and molecule flexibility. The membrane acts as a sieve to retain dissolved
and suspended materials that are physically too large to pass throug its pores.
The major difference between UF and NF is the molecular weight of separated
species. Both methods utilise identical operating principles.
Electrodialysis relies on ion-exchange membrane in a direct-curent electrical
field to separate inorganic ionic species from solution. Like reverse osmosis
membranes, electrodialysis membrane are sensitive to fouling that limit waste-
treatment application of this technology. The metal-finishing and electroplating
industry is the greatest potential market for these systems.
Membrane separation – ultrafiltration, nanofiltration,
electrodialysis
The applicability of chemical treatment to waste depends upon the chemical
properties such acid-base, oxidation-reduction, precipitation, reactivity,
flammability, corrosivity and compatibility with other wastes. An attractive
feature of chemical treatment is the opportunity to treat wastes with other
wastes, e.g. mutual neutralisation of waste acids with waste bases.
It consists especially of:
- acid/base neutralisation
- chemical precipitation
- chemical flocculation
- oxidation/reduction
- chemical extraction and leaching
- ion exchange
Methods of chemical treatment
Neutralisation is a process used to eliminate waste acids and bases as
shown by the following reaction:
H+ + OH- → H2O
Although simple in principle, neutralisation can present some problems in
practice, such as evolution of volatile contaminants or mobilisation of soluble
substances. The heat generation from the above reaction when the waste
envolved are relatively concentrated can result in dangerous hot solution
and even spattering. Strongly acidic or basic solutions are corrosive to
pipes, containers and mixing apparatus.
Lime (Ca(OH)2) is a widely used base for treating acidic wastes. Sulphuric
acid (H2SO4) is a relatively inexpensive acid for treating alkaline wastes.
However, addition of too much sulphuric acid can produce highly acidic
products. For some applications, acetic acid (CH3COOH), is preferable. It is
a weak acid and also naturalproduct and biodegradable.
Neutralistion, or pH adjustment, is often required prior to the application
of other waste treatment processes (biochemical treatment –
microorganisms usually require a pH range of 6 to 9.
Acid/base neutralisation
Oxidation and reduction can be used for the treatment and removal of a variety of
inorganic and organic wastes. The net result of these reactions is the conversion of the
waste to a nonhazardous form or to a form that can be isolated physically.
Ozon, O3, is a strong oxidant that can be generated on-site by an electrical discharge
through dry air or oxygen:
3O2 → 2O3
electrical discharge
Oxidation of organics
(CH2O) + (O) → CO2 + H2O
organic matter
Oxidation of inorganics
Cyanide: 2CN- + 5 OCl- + H2O → N2 + 2HCO3- + 5Cl-
Iron (II): 4 Fe2+ + O2 + 10 H2O → 4 Fe(OH)3 + 8H+
Reduction of inorganics
Chromate 2CrO42- + 3 SO2 + 4H+ → Cr2(SO4)3 + 2H2O
Permanganate MnO4- + 3Fe2+ + 7 H2O → MnO2(s) + 3 Fe(OH)3 (s) + 5 H+
Oxidation/reduction
Precipitation is used in hazardous waste treatment primarily for the removal of
heavy metal ions from water as shown for the chemical precipitatiopn of
cadmium:
Cd2+ (aq) + HS- → CdS (s) + H+ (aq)The most widely used means of precipitation metal ions is by the
formation of hydroxides such as chromium (III) hydroxide:
Cr3+ + 3 OH- → Cr(OH)3
The source of hydroxide ions, OH-, is a base (alkali), such as lime (Ca(OH)2,
sodium hydroxide (NaOH), or sodium carbonate (Na2CO3).
Sulfide precipitation is very effective means of treatment, because the
solubility of some heavy metal sulfides is extremely low. Sources of sulfide
ions include sodium sulfide, Na2S, sodium hydrosulfide (NaHS), hydrogen
sulfide (H2S), and iron (II) sulfide.
Some metals can be precipitated from solution in the elemental metal form by
the action of a reducing agent (e.g. sodium borohydride, NaBH4).
Metal ions can be converted to the elemental form and removed from solution
by reaction with more active metal by a process called cementation – the
reduction of toxic cadmium with relatively harmless zinc:
Cd2+ + Zn → Cd + Zn2+
Chemical precipitation
Electrolysis consists of the electrochemical reduction and oxidation of
chemical species in solution by means of electricity applied to electrode from
an external source. One species in solution (usually a metal ion) is reduced
by electrons at the cathode and another gives up electrons to the anode and
is oxidised there.
Cathode (-) Anode (+)
Cu2+ + 2e- → Cu H2O → ½ O2 + 2e- + 2H+
In hazardous waste application electrolysis is most widely used in recovery
of metals, mostly from electroplating media, from wastewater and rinsewater
from the electronics industries and from metal finishing operations.
The metals that are most commonly recovered by electrolysis are cadmium,
copper, gold, lead, silver and zinc.
Recovered metals are usually recycled to the process that produces the
waste.
Electrolysis
Chemical extraction or leaching in hazardous waste treatment is the removal
of a hazardous constituents by reaction with extractants in solution.
Acidic solutions dissolve poorly soluble heavy metal salts by reaction of the
salt anions with H+.
PbCO3 + H+ → Pb2+ + HCO3-
Ion exchange
Ion exchange is a means of removing cations or anions from solution onto a
solid resin. Ions taken up by an ion exchange resin may be removed by
treating the resin with concentrated solutions of acid, base or salt (NaCl).
The net result is to concentrate the ions originally removed from dilute
solution in water into a much more concentrated solution.
The greatest use of ion exchange in hazardous waste treatment is for
removal of low level of heavy metal ions from wastewater. Ion exchange is
employed in the metal plating industry to purify rinsewater and spent plating
bath solution.
Chemical extraction and leaching
Influence of pH and other chemical variables on leaching.
pH value – major chemical variable controling the leaching of minor and major
elements from waste or residue.
pH value influenced the solubility of important minerals (oxides, hydroxides,
carbonates).
Cationic and anionic constituents are bound to these solid residues by
adsorption/desorption on mineral surface with a pH-dependent charge.
Leaching of cationic constituents increases towards low pH, anionic constituents
towards high pH.
Calcium – typical cation leaching behaviour (concentration increase towards low pH).
Molybdenum is present as the oxyanion molybdate (MoO42-) – leaching
concentration increasing towards high pH.
Amphoteric behaviour of e.g. Pb and Zn that can be present both in cationic and
anionic form, show substantial and increasing leachability both at low (cationic form)
and high (anionic form) pH value.
The general leaching behaviour can be further modified by the effect of other
chemical parameters (redox potential, complexation of inorganic components).
Leaching properties of waste or residue
Photolytic reactions or the process of photolysis are those in which
protons or electromagnetic radiation consisting of shortlwavelenght
visible light or ultraviolet radiation are absorbed by a molecule,
causing a chemical reaction to occur.
Photolysis can be used to destroy a number of kinds of hazardous
wastes. In such applications it is most useful in breaking chemical
bonds in refractory organic compounds.
Photolysis can be used to destroy several kinds of hazardous waste
substance, such as dioxins, herbicides (atrazin), 2,4,6-trinitrotoluene
(TNT) and polychlorinated biphenyls (PCB).
The addition of chemical oxidant such as potassium peroxodisulfate
K2S2O8, enhances destruction of oxidising active photolytic products.
Photolytic reactions
Chemical treatment of hazardous waste:
neutralization, precipitation, oxidation-reduction
J.Pichtel: Waste Management Practices, ISBN:978-1-4665-8519-5
Explosive: substances and preparations which may explode under the effect of flame or
which are more sensitive to shocks or friction than dinitrobenzene.
Oxidizing: substances and preparations which exhibit highly exothermic reactions when in
contact with other substances, particularly flammable substances.
Flammable: liquid substances and preparations having a flash point equal to or greater than
21°C and less than or equal to 55°C.
Highly flammable: liquid substances and preparations having a flash point below 21°C
(including extremely flammable liquids), or substances and preparations which may become
hot and finally catch fire in contact with air at ambient temperature without any application of
energy, or solid substances and preparations which may readily catch fire after brief contact
with a source of ignition and which continue to burn or to be consumed after removal of the
source of ignition, or gaseous substances and preparations which are flammable in air at
normal pressure, or -substances and preparations which, in contact with water or damp air,
evolve highly flammable gases in dangerous quantities.
Irritable: non-corrosive substances and preparations which, through immediate, prolonged or
repeated contact with the skin or mucous membrane, can cause inflammation.
Harmful: substances and preparations which, if they are inhaled or ingested or if they
penetrate the skin, may involve limited health risks.
(Appendix) PROPERTIES OF WASTES WHICH RENDER THEM HAZARDOUS
Toxic: substances and preparations (including very toxic substances and preparations)
which, if they are inhaled or ingested or if they penetrate the skin, may involve serious, acute
or chronic health risks and even death.
Carcinogenic: substances and preparations which, if they are inhaled or ingested or if they
penetrate the skin, may induce cancer or increase its incidence.
Corrosive: substances and preparations which may destroy living tissue on contacts.
Infectious: substances containing viable micro-organisms or their toxins which are known or
reliably believed to cause disease in man or other living organisms.
Teratogenic: substances and preparations which, if they are inhaled or ingested or if they
penetrate the skin, may induce non-hereditary congenital malformations or increase their
incidence.
Mutagenic: substances and preparations which, if they are inhaled or ingested or if they
penetrate the skin, may induce hereditary genetic defects or increase their incidence.
Substances and preparations which release toxic or very toxic gases in contact with water,
air or an acid.
Substances and preparations capable by any means, after disposal, of yielding another
substance, e.g. a leachate, which possesses any of the characteristics listed above.
Ecotoxic: substances and preparations which present or may present immediate or delayed
risks for one or more sectors of the environment
Questions related to the presentation
- Which type of waste is mainly processed by physico – chemical
techniques?
- Principal physical processes for waste treatment.
- Principles of membrane separation.
- Principal chemical processes for waste treatment.
- Interrelationship between physical and chemical processing of waste.
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